Good morning.Where can we avail of a 24hr transit visa?Should we get it fr our country or origin?

If you are talking about the type G transit visa, you need to pay a fee and get it from your local Chinese embassy. If it's visa-free transit you are talking about, it's free and you'll get it when clearing immigration in Shanghai, however the officer has the power to refuse you entry for any reason (and that happens very frequently).

Hi does it still need transit visa if I have 24hrs lay over in pudong China?

We were on a 12 hr layover in Shanghai from Manila to Los Angeles. We were refused a 24 hr transit visa by the immigration officer there. They just said that they changed the policy last Feb 1. We were there Feb 4. Other folks from other nationalities were refused entry as well.

Just a note, Jan 14 from LAX to MNL, I also has a 19 hr layover in Shanghai, but back then I was allowed to go out the city.

Do you mean you were refused permission to leave the airport?
Did you go through customs when you exited the plane , even to go to the transit waiting area, or did you go to customs because you wanted to leave the airport?